Having used both of these on duty over several years, you might find my comments interesting...

To my way of thinking, each gun has its strengths and weaknesses.
The right choice is to pick a gun which will be effective in the circumstances you will use it in. Try not to decide on a particular piece just because "it looks cool" or something like that.

I used a 4" 357 magnum as my daily carry for around 5 years. If you're carrying all the time you might want to get a stainless steel gun becasue they tolerate daily use better.(I had stainless, some guys had blued finish which looked pretty rough after a couple of years).

357 PROS:
* simple point-and-click interface
* you can use 38spl ammo for cheaper practice (back then, not sure if 38spl is still cheaper)
* good CQB weapon if you're up close (ie: pistol-whip anyone?)
* very good ballistics compared to 9mm.
* very safe in daily use compared to automatic pistols.
* grips can be customised to fit your hand

357 CONS:
* a pain to carry on the hip, much more so if you're constantly getting in and out of vehicles. It's a lot more accessible and comfortable in a shoulder holster if you're in a vehicle. (it's not a problem if you're on horseback or motorcycle).
* quite heavy in a shoulder holster, tend to sag during the course of a day no matter how good a holster you get.
* limited round capacity (y'all know that anyway)

Moving on to the G17, another piece I lived with daily for over 5 years. The polymer frame and specially coated slide are very resistant to daily exposure to body sweat and the inevitable bumps and scrapes. Having extensive experience with revolvers, it is easy to see why most police departments have moved to this type of weapon.

G17 CONS:
* polymer frame and magazines could be harmed by heat or solvents. (could someone confirm or refute?)
* less power than the 357, somewhat compensated by the high round capacity.
* not as safe as revolvers for everyday carry. (in my opinion)

Sentimentally speaking, I would always pick the 357.
Any modern S&W revovler looks like a work of art to me, such beautiful craftsmanship.
However, when practicality is taken into account then the obvious choice in most circumstances would be a modern pistol for everyday carry.

The only negative point I have against semi-automatics is that they are inherently less safe than revolvers. This is in MY experience, since I have seen a glock go off when the slide was released after reloading. This could have been as a result of the users mishandling of the weapon. Nevertheless, a negligent discharge seems far less likely with a revolver to me.
My advice to anyone would be to shoot as many different guns as possible before deciding on one for yourself.

One big point in the revolvers favour is what I like to refer to as the point-and-click interface. That is, providing you always have fresh ammo, you know when the trigger is pulled it will go bang. Automatics are more likely to misfire after they've been carelessly bouncing around in your glovebox for a month. As I said earlier, it all depends on individual circumstances.

The one time some nut pulled a gun on me, it was a colt45. As he swung it from the small of his back he managed to release the magazine, which conveniently landed at my feet. lucky for him I hate paperwork...

Take what I say with a grain of salt, since I know this is a contentious subject among shooters. My operating environment was mostly close-quarter personal protection of people. These are my opinions developed over many years in that context, I'd love to hear what others think from different operating environments.

Personally, I would choose the smaller G26 for an everyday carry or the bigger calibre model (G28 I think - .40cal) but I'm pretty sure those are prohibited in my country even for most law-enforcement agencies whereas the G26 is not.
If I was going for a revolver in the same circumstances, I'd go for a 5-shot 2 1/2" "chief special" snub-nose revolver.

Sadly, all of these are fond memories now and we have draconian, fascist gun control laws in Australia. Now that I live among the sheeple, I don't have a hope of having anything like a concealed-carry permit. I could go to a lot of time, trouble and expense to fulfill the requirements of private gun ownership but it is just too much so I go overseas for recreational shooting these days.

I hope patriotic Americans NEVER lose the right to own and bear arms.
That would be the final evidence that we are living under worldwide totalitarian control.

G17 CONS:
* polymer frame and magazines could be harmed by heat or solvents. (could someone confirm or refute?)
* less power than the 357, somewhat compensated by the high round capacity.
* not as safe as revolvers for everyday carry. (in my opinion)

Kind of an odd comparison if you ask me. Why choose a 9mm in a semi-auto if you would have .357 in a wheelgun? I could name other semi-autos that are as least as reliable as the Glock with a much more comfortable pistol grip; but between the two you have mentioned I would say choose the Glock; but update to .40 S&W (used by most cops), .357 SIG (a great round; but more expensive and rare, I use it for my daily carry piece, same mag capacity as .40, used by the Secret Service) or .45 ACP (the only semi-auto round to be effective with FMJ bullets; the US military is slowly switching back to it). 10mm Norma is the best semi-auto round; but it's too rare and expensive and almost all factory loads are less than full power. Ideally, if you have the money, the best way to go would be a Glock 20 with barrels in 10mm, .40 and .357.